The influence of the expansion of winter crop proportion in the rotation structure on soil biological activity

D. Janušauskaitė¹ and A.Velykis²

¹Plant Pathology and Protection Department, Lithuanian Research Centre forAgriculture and Forestry Akademija, Dotnuva, Kedainiai District, Lithuania, LT-58344; e-mail: daliaj@lzi.lt
²Joniskelis Experimental Station, Lithuanian Research Centre for Agriculture and Forestry,Joniskelis, Pasvalys District, Lithuania, LT-39301; e-mail: velykisalex@gmail.com

Abstract:

The effect of the expansion of the winter crop proportion in the crop rotation structure under conditions of conventional (ploughing) and sustainable (reduced) soil tillage on soil biological properties was investigated on a clay loam Gleyic Cambisol at the Joniskelis Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry over the period 2004–06. The effect of a different proportion of winter crop in the rotation on microbial populations in soil was influenced primarily by the weather conditions during the growing seasons. In different years, the number of ammonificators ranged from 5.68 to 28.37 mln g-1, the number of mineralizators ranged from 8.23 to 37.01mln g-1, fungi from 28.55 to 101.46 thousand g-1 of soil. The soil microbial amount was higher under wetter conditions. The numbers of microbes differed between soil tillage systems and had diverse impact. The number of ammonificators did not differ markedly between the soil tillage treatments; however, the number of microbes in the conventionally tilled plots exceeded that in the sustainable tillage system by 5.57%. The sustainable tillage system was positive for N assimilators and fungi. Increasing the winter crop in the rotation did not exert any strong positive effect on all microbes. Increasing the winter crop proportion was favourable for micromycetes. More bacteria were found in the rotation with 25% of winter crop, more mineral N assimilators were found in the rotation with 25% and 50% of winter crop, and fungi max under 50%, 75% and 100% of winter crop in the rotation.

Key words:

Clayey Cambisol, crop rotation, soil microbes, soil tillage, winter crops

Soil protection value of winter crops and reduced tillage on clay loams

A. Velykis and A. Satkus

Joniskelis Research Station of the Lithuanian Institute of Agriculture, Joniskelis, LT-5240 Pasvalys District, Lithuania;
Tel/fax: 370-71-38224; e-mail: joniskelio_lzi@post.omnitel.net

Abstract:

Experiments to reduce soil physical degradation were carried out at Joniskelis Research Station of the Lithuanian Institute of Agriculture over the period 1998–2002. The soil of the experimental site is characterised as glacial lacustrine clay loam on silty clay (Gleyic Cambisol). The following was investigated: Factor A. Crop rotations with different proportions of winter and spring crops (1. Without winter crops; 2. Winter crops 25%; 3. Winter crops 50%; 4. Winter crops 75%; 5. Winter crops 100%), growing annual and perennial grasses, spring and winter wheat, triticale, and barley. Factor B. Soil tillage systems: 1. Conventional (primary soil tillage was performed by ploughing); 2. Sustainable (after grasses the soil was ploughed, after other preceding crops the soil was loosened without inverting the topsoil). Our experimental evidence suggests that increasing winter crops in the crop rotation reduced compaction of the topsoil from high to moderate, maintained up to 37.3% of higher productive moisture reserves, improved water to air ratio, and increased the crop rotation productivity up to 44.7%. The application of reduced primary tillage in a sustainable system had persistence of high soil compaction and 8.0% lower air-filled porosity at the bottom of the topsoil, but the whole topsoil reached physical maturity more evenly in the spring. The grain yield of cereals was 6.4% lower compared with the yield after conventional soil tillage. On these clay loam soils, spring cereals were more sensitive (poorer performance) to reduced soil tillage compared with winter cereals.

Key words: